Algemeen

The Ebro Delta is a wetland area in which natural ecosystems have been partially replaced by rice fields. This mixed and productive landscape has allowed the establishment of a rich community of organisms. The viperine snake Natrix maura has traditionally been a common and abundant predator because the habitat is favorable and prey availability is high. In June 1995, we conducted a demographic study to evaluate relative densities of snakes in the rice fields. Thirteen years later, we repeated the same study in the same area and season. The field work consisted of 29 censuses of one hectare each, and snakes and their potential prey (green frogs and fish) were counted. In 1995, we found 27 snakes (0.93 animals/ha), these occupying 48% of the sites. Frogs and fish were observed in 23 of the 29 censuses (79%). In 2008, no snakes were found and frogs and fish appeared in only 11 of the samples (38%).

Long-term studies have revealed population declines in fishes, amphibians, reptiles, birds and mammals. In birds, and particularly amphibians, these declines are a global phenomenon. Among reptiles, snakes are top predators and therefore a decline in their numbers may have serious consequences for the functioning of many ecosystems. Our results show that, of 17 snake populations (eight species) from the UK, France, Italy, Nigeria and Australia, 11 have declined sharply over the same relatively short period of time. "All the declines occurred during the same relatively short period of time and over a wide geographical area that included temperate, Mediterranean and tropical climates," write the authors. "We suggest that, for these reasons alone, there is likely to be a common cause at the root of the declines and that this indicates a more widespread phenomenon." Although the paper stresses there is no proof of the cause of the losses, the researchers say they "suspect" loss or deterioration of habitats and declining prey are among the main problems faced by snake populations.

Former Senator Juan Miguel Zubiri on Sunday said the Philippine cobra (Naja philippinensis) and 12 other reptiles have joined the official list of threatened species. In a statement, he said the snake was earlier identified near threatened but its declining population required its change in category. A highly venomous burly snake averaging a meter in length, Naja philippinensis thrives in low-lying plains, from thick jungles and forested areas to open fields and grasslands. It preys mostly on small rodents and frogs and occasionally, other snakes, lizards and birds. Predators of the Philippine cobra include humans, birds of prey, the king cobra, and the mongoose.
Zuniry, former chairman of the Senate environment and natural resources committee, said the other threatened species are the Loggerhead turtle (Caretta caretta), Southeast Asian box turtle (Cuora amboinensis), Spiny terrapin (Heosemys spinosa), South-east Philippine spitting cobra (Naja samarensis), Equatorial spitting cobra (Naja sumatrana), King cobra(Ophiophagus hannah), Southeast Asian softshell turtle (Pelochelys bibroni), Batanes pit viper (Trimeresurus flavomaculatus), Panay monitor lizard (Varanus mabitang) and three subspecies of the Malay monitor lizard. Of the 13 newly threatened reptiles, Zubiri, Pilipinas EcoWarriors convenor, said the Panay monitor lizard was labeled critically endangered. The rest were tagged either vulnerable or endangered.

The severe global extinction crisis facing amphibian populations around the world may be mirrored in reptiles like snakes, lizards, turtles and crocodiles. A scientific study cites evidence that recent scientific research into amphibian declines far outweighs research into reptile declines, even though both groups of species may be facing a similar extinction threat. In May 2008, studies commissioned by the European Commission and carried out by IUCN, found that Europe's reptiles and amphibians were in similar degrees of trouble. 22.9% of Europe's native amphibian species were categorised as threatened with extinction, and 19.4% of reptiles. The study also reported that 4.3% of reptile species in Europe were listed as Critically Endangered, the most serious of the Red List categories. This is double the number of amphibians in the same category. "It is increasingly clear that amphibians are not alone in facing a major biodiversity crisis," said lead author Professor Trevor Beebee of the University of Sussex. "Other groups of ‘cold blooded' vertebrates, notably reptiles and freshwater fishes, are in the same boat."

“Critically endangered” is the highest threat level that can be assigned to a wild species (lower levels are “endangered” and “vulnerable”). These species are either facing an extremely high risk of extinction, or have numbers which decreased (or will) by 80% within three generations. Some of these species may already be extinct.